align_str_left <- function(x, pad_n = NULL) {
  if (is.null(pad_n)) pad_n <- max(nchar(x))
  right <- strrep(" ", pad_n - nchar(x))
  paste0(x, right)
}
align_str_right <- function(x, pad_n = NULL) {
  if (is.null(pad_n)) pad_n <- max(nchar(x))
  left <- strrep(" ", pad_n - nchar(x))
  paste0(left, x)
}
align_str_center <- function(x, pad_n = NULL) {
  if (is.null(pad_n)) pad_n <- max(nchar(x))
  left <- strrep(" ", ceiling((pad_n - nchar(x)) / 2))
  right <- strrep(" ", floor((pad_n - nchar(x)) / 2))
  paste0(left, x, right)
}

#' @export
#' @keywords internal
#' @noRd
print.modelsummary_markdown <- function(x, ...) {
  cat("\n\n")
  cat(x, sep = "\n")
}


#' Internal function to build table with `markdown`
#'
#' @inheritParams factory_gt
#' @noRd
#' @return tinytable object
factory_markdown <- function(
  tab,
  align = NULL,
  hrule = NULL,
  hgroup = NULL,
  hindent = FALSE,
  notes = NULL,
  title = NULL,
  escape = TRUE,
  output_format = "markdown",
  output_file = NULL,
  ...
) {
  # fake spans
  colnames(tab) <- gsub("\\|{4}", " / ", colnames(tab))

  # align content
  for (i in seq_along(tab)) {
    pad_n <- max(nchar(colnames(tab)[i]), max(nchar(tab[[i]])))
    if (align[[i]] == "l") {
      tab[[i]] <- align_str_left(tab[[i]], pad_n = pad_n)
    } else if (align[[i]] == "r") {
      tab[[i]] <- align_str_right(tab[[i]], pad_n = pad_n)
    } else if (align[[i]] == "c") {
      tab[[i]] <- align_str_center(tab[[i]], pad_n = pad_n)
    }
  }

  # bind centered column names
  header <- as.data.frame(as.list(colnames(tab)))
  colnames(header) <- colnames(tab)
  for (i in seq_along(tab)) {
    header[[i]] <- align_str_center(header[[i]], nchar(tab[[i]][1]))
  }
  tab <- rbind(header, tab)

  # pipes
  tab[[1]] <- paste("|", tab[[1]])
  for (i in seq_along(tab)) {
    tab[[i]] <- paste(tab[[i]], "| ")
  }
  tab <- do.call(paste0, tab)

  # ruler
  ruler <- gsub("[^\\|]", " ", tab[1])
  ruler <- gsub(" ", "-", ruler)
  ruler <- gsub("-\\|", ":|", ruler) # all except first
  ruler <- sub(":\\|", "-|", ruler) # all except first
  ruler <- sub("\\|-", "|:", ruler) # only first
  ruler <- gsub("-$", "", ruler) # only first

  # group ruleers
  for (i in rev(seq_along(hgroup))) {
    tab <- append(tab, ruler, after = hgroup[[i]][2] + 1)
  }

  # horizontal rulers: knitr and pandoc may not support headers, or I don't know how
  # hrule <- rev(sort(c(1, hrule)))
  hrule <- 1
  for (h in hrule) {
    tab <- append(tab, ruler, after = h)
  }

  # title
  if (!is.null(title)) {
    tab <- c(paste("Table:", title), "", tab)
  }

  # notes
  if (!is.null(notes)) {
    for (n in notes) {
      tab <- c(tab, "", "__Note:__", paste("^^", n))
    }
  }

  # output
  class(tab) <- c("modelsummary_markdown", "knitr_kable")
  attr(tab, "format") <- "pipe"

  # output
  if (is.null(output_file)) {
    return(tab)
  } else {
    writeLines(paste(tab, collapse = "\n"), con = output_file)
  }
}

# 'knitr_kable' chr [1:24] "Table: Blah blah" "" "|             |   (1)    |" "|:------------|:--------:|" "|(Intercept)  |  26.664  |" "|             |  (0.972) |" "|factor(cyl)6 |  -6.921  |" ...
# - attr(*, "format")= chr "pipe"

#     Table: Blah blah
#
# |             |   (1)    |
# |:------------|:--------:|
# |(Intercept)  |  26.664  |
# |             |  (0.972) |
# |factor(cyl)6 |  -6.921  |
# |             |  (1.558) |
# |factor(cyl)8 | -11.564  |
# |             |  (1.299) |
# |Num.Obs.     |  32      |
# |R2           |   0.732  |
# |R2 Adj.      |   0.714  |
# |AIC          | 170.6    |
# |BIC          | 176.4    |
# |Log.Lik.     | -81.282  |
# |F            |  39.698  |
# |RMSE         |   3.07   |
#
# __Note:__
# ^^ a
#
# __Note:__
# ^^ b
